Nowadays, the height of buildings holding construction records is close to or in excess of 1000 m (39370 in). The construction of such towers does not necessarily conform to economic prerogatives, but rather to a preoccupation to take up a technological challenge that certain builders impose on themselves in order to show their boldness and their skill. Such towers, in fact, give rise to technological problems that are very difficult to solve using current techniques and materials.
The first of said difficulties is related to wind resistance. The weight and the ground pressure can be resolved easily enough using high-performance materials and sections that are more or less large.
However, the fact that a tower can sway or become unstable in the wind is much more complicated to overcome.
In order to define an optimized form for towers, use is generally made of trials undertaken in wind tunnels, however in spite of optimizing the geometric configuration of the towers, their swaying remains a serious handicap.
So as to remedy these problems, damping systems which are intended to prevent or limit the amplitude of the swaying are often used.
Such systems absorb a large part of the energy introduced into the primary structure of the buildings and influence the dynamic behaviour of the structure.
A large number of types of damping systems exist in this regard. They are often made up of oscillating ballast weights which are placed close to the top of the buildings and which are braked by being connected to the structure by means of dampers.
The ballast weights are, for example, mounted on sliding or rolling systems or are simply suspended by means of one or several hangers.
The common point of said devices is the need to arrange large ballast weights.
For example, for a tower which is 1000 m (39370 in) in height, the ballast necessary within said type of damping device can have a weight in the vicinity of 1000 tonnes (1101.31 short tons).
Bringing such weights to a great height gives rise to a problem of conveying materials. The ballast components conventionally used are in the form, for example, of metal pigs that are conveyed by means of site cranes. Said operation blocks the cranes for long periods and paralyzes the progress of the rest of the construction, which has tangible repercussions on the construction costs and the corresponding delays.